Surface coverings such as decorative decals, stripes, graphics, emblems, and protective moldings are used extensively in a variety of applications. These surface coverings are typically adhered with pressure-sensitive adhesives to painted and unpainted surfaces of automobiles, trucks, airplanes, and boats. The pressure sensitive adhesives typically are based on acrylic polymers or elastomers which may have been modified by the addition of tackifiers and stabilizers to enable the surface covering item to adhere to the surface by finger or roller pressure.
In the process of repairing and repainting portions of a painted surface to which the surface coverings are adhered, removal of the coverings may be necessary. Removal of relatively thin surface coverings such as decals and pinstripes is presently done by rotating an eraser unit or soft elastomeric discs at high speeds against the workpiece. This rotation generates adequate heat to cause the adhesive to lose its adhesion and thus release the surface coverings so they can be removed without damaging the painted surface. As it rotates against a workpiece, the eraser unit or soft elastomeric discs will be used up as a result of extensive usage.
One eraser unit for removing such surface coverings is disclosed in Fisher (U.S. Pat. No. 5,259,914). This patent discloses an disc-shaped eraser unit with a flat disc embedded inside the eraser member. The disc has a central opening and two rim notches. When molding the rubber eraser member with the disc embedded, the rubber material will fill the two rim notches. A bolt having an elongated shaft extends through the central opening of the disc and is secured by a nut and washer. The elongated shaft extending out from the eraser member is attaching to a rotating drive means. As the eraser unit rotates against a workpiece, the outer periphery is worn down and renewed.
Because of the minimal mechanical interlock between the embedded disk and eraser material of Fisher, that system relies on a sufficiently high adhesion between the embedded disk and material and sufficiently high strength of the eraser material to prevent the embedded disk from shearing loose and spinning freely within the eraser. Therefore, such a system would not be suitable for applications in which there is a weaker adhesion between the disk or drive means and the eraser material or in which there is a lower strength eraser material.
For convenience, it is also desirable to visually perceive the disc embedded inside the eraser member during use to indicate the life of the eraser material remaining and to avoid damaging the workpiece by rotating the embedded disc accidentally against the workpiece.
Another apparatus used to remove the surface coverings described above is a soft elastomeric discs is disclosed in Winter (U.S. Pat. No. 5,269,874). This patent discloses a rotatable body comprising at least one disc of elastomer and spacers secured to an arbor and drive means.
Co-pending application "Portable Apparatus for Removing Heat Softenable Surface Coverings," U.S. patent application Ser. No. 08/868,915, now U.S. Pat. No. 5,879,504, discloses a filled elastomeric composition that comprises an elastomer, about 2 to 43 wt-% of an organic lubricant selected from the group consisting of solid organic lubricants and polar organic lubricants and about 2 to 43 wt-% of a non-abrasive particulate, wherein the organic lubricant and the non-abrasive particulate together comprise about 4 to 45 wt-% of the filled elastomeric composition that is useful for removing surface coverings described above.